1. Field of the Invention
Hand-held power tools are in common use for many purposes in industry. Typical examples are the electrically operated hand-held drill, and the pneumatically operated hand-held fastener placing tool. The latter may be arranged to place fasteners of various types, e.g. self-tapping screws, threaded inserts, or blind rivets. Since the tool, in use, will have to be positioned accurately, it must be possible for the operator to hold it securely in his or her hand (or maybe in both hands), in order to support the tool, to position the tool accurately, and maybe to support the mechanical reaction to the action of the tool in use. Accordingly the tool is provided with a suitably shaped and surfaced grip, often in the form of a pistol grip projecting transversely from the tool body. The tool is also provided with a trigger, in the appropriate position in relation to the grip, for operating by a finger of the operator's hand. This grip, and the location of the trigger, are fixed in relation to the body of the tool (although, of course, the trigger is able to move through a relatively small distance when operated).
2. Discussion of the Background
There has recently arisen a requirement for power operated tools to be mounted pointing downwards vertically above a workpiece or worktable, in such a way that the tool can be moved across the work to act on different locations thereon while gripped, guided and activated by the operator's hand. One common arrangement is for the tool to be mounted on a radial arm of adjustable length, e.g. a pantograph arm. The inboard end of the arm, about which the arm rotates, is mounted at the back of the worktable, while the operator stands or sits in front of the worktable. As the tool is moved around over the work, the angular relationship of the tool body, and therefore of the trigger, to the operator's hand, changes. Consequently the operator cannot maintain his grip on the tool body and cannot readily operate the tool trigger. It may be more economical to utilize an existing standard or slightly modified hand-held tool for such a purpose, instead of designing and constructing a special version of the tool. However, such use introduces some practical problems, such as the changing angular relationship just mentioned. The present invention is intended to overcome such a problem.